Thread handling systems and devices for sewing machines



M. WIENER Jan. 23, 1968 THREAD HANDLING SYSTEMS AND DEVICES FOR SEWING MACHINES 4 Sheets-Sheet 1 Filed Feb. 10. 1966 V 8 mm mm mm mm INVENTOR. Melvin Wiener WITNESS Z. A TORNEY M. WIENER 3,

THREAD HANDLING SYSTEMS AND DEVICES FOR SEWING MACHINES Jan. 23, 1968 4 Sheets-Sheet 2 INVENTOR. Melvin Wiener TTORNEY Filed Feb. 10 1966 Jan. 23, 1968 M. WIENER 3,364,889

THREAD HANDLING SYSTEMS AND DEVICES FOR SEWING MACHINES Filed Feb. 10. 1966 4 Sheets-Sheet 5 Fig.9

I NVEN TOR.

Melvin Wiener wmvess M. WIENER 3,364,889 THREAD HANDLING SYSTEMS AND DEVICES FOR SEWING MACHINES Jan. 23, 1968 4 Sheets-Sheet 4 Filed Feb. 10. 1966 WI TNESS United States Patent Ofifice 3364,39 Patented Jan. 23, 1%68 3 364 889 THREAD HANDLING sisrnMs AND nnvrcas FGR SEWING MACHINES Melvin Wiener, Rockaway, NJL, assignor to The Singer Company, New York, N.Y., a corporation of New .l'erse y Filed Feb. 10, 1966, Ser. No. 537,586

5 Claims. (Cl. 112245) ABSTRACT OF THE DISCLOSURE A thread handling system for the sewing threads of a sewing machine is disclosed in which the thread is directed to a stitch forming instrumentality through a conduit into which compressed air is directed to impose tension on the thread and to take-up thread by aerodynamic friction. A novel thread container is also disclosed for storing without tangling the slack thread which is taken up by the thread handling system.

This invention relates to thread handling systems and devices for sewing machine, and more particularly to systems and devices for handling thread by compressed air during stitch formation.

In a typical sewing machine, thread from a supply of needle thread must pass through numerous thread guides, a thread tension device, a check spring on the thread tension device, a thread take-up lever and sometimes a slack thread regulator on its way to the needle. The foregoing mechanisms are necessary for proper thread handling to form uniform stitches. In general, the thread take-up lever serves to manipulate a bight of thread containing the approximately three and one half inches of slack thread which results as the needle withdraws from work material during its upstroke. The action of the thread take-up lever culminates in a definite jer which sets the stitch. Tension is imposed on the thread by the thread tension device, and the check spring serves to take-up excessive slack thread permitted by the thread take-up lever as the needle perform its downstroke to penetrate the work material. If slack thread is allowed to form as the needle begins its downstroke, the needle may penetrate the thread and break the thread or the thread may wrap around the point of the needle and be broken by the under stitchforming mechanism. A slack thread regulator may be provided to compensate for irregular thicknesses of work material and hence irregular thread length requirements for stitches. The slack thread regulator is actuated by the presser foot and holds a bight of needle thread. As the presser foot moves up and down over irregular thicknesses of work material, the slack thread regulator moves up and down with the presser foot to vary the size of the bight of thread.

From the foregoing, it is evident that proper thread handling is a complex problem requiring numerous mechanisms for its solution. Both the thread tension device and the thread take-up lever require complicated mechanisms which substantially increase the cost of the sewing machine. In addition, the oscillating action of the thread take-up lever induces machine vibrations which are especially detrimental at high speeds. Thread handling for under stitch-forming mechanisms presents closely analogous problems.

It is, therefore, an object of this invention to provide pneumatic thread handling systems and devices for sewing machines.

Another object of the invention is to provide thread handling systems and devices which cause only inconsequential machine vibrations.

Another object of the invention is to provide thread handling systems and devices which require much fewer parts, are simpler, and are much more economical then conventional thread handling systems.

The main feature of the invention is the provision for thread handling systems for sewing machines in which thread is threaded through a conduit and moves toward a stitch-forming mechanism as required by the stitchforming mechanism to form stitches. Air is caused to flow through the conduit counter to the movement of the thread to set stitches by imposing tension on the thread and taking up slack thread by aerodynamic friction. Suitable sources of compressed air are commonly available in modern industrial facilities.

Other objects and a fuller understanding of the invention may be had by referring to the following description and claims, taken in conjunction with the accompanying drawings in which:

FIG. 1 is a front perspective view partly in section of a sewing machine incorporating a pneumatic needle-thread handling system employing the concepts of a first modification of the invention;

FIG. 2 is a top perspective view of a modified rotary loop-taker having an additional thread guide and a foreshortened loop-controlling tail for use with the modification of FIG. 1;

FIG. 3 is a top plan view of the additional thread guide of FIG. 2;

FIG. 4 is a front perspective view of a sewing machine incorporating a pneumatic needle-thread handling system employing the concepts of a second modification of the invention;

FIG. 5 is a detail cross sectional view of the outlet for thread of the conduit shown in FIG. 4;

FIG. 6 is a front elevational view of a first variation of the modification of FIG. 4;

FIG. 7 is a front elevational view of a second variation of the modification of FIG. 4;

FIG. 8 is a front elevational view of a third variation of the modification of FIG. 4;

FIG. 9 is a front perspective view of a sewing machine incorporating a pneumatic looper-thread handling system employing the concepts of a third modification of the invention; and

FIG. 10 is a front perspective view of a variation of the modification of FIG. 9.

With reference to the drawings, a first modification of the invention is illustrated in FIGS. 1 to 3. The first modification of the invention is illustrated as embodied in a sewing machine having a frame including a work-supporting bed 20, a standard (not shown) rising from one end of the Work-supporting bed, a bracket arm 22 at the top of the standard overhanging the work-supporting bed, and a hollow sewing head 23 at the free end of the bracket arm. The work-supporting bed is housed in a recess 24 in a sewing table 25.

Mounted inside the hollow sewing head is a lower needle bar bushing 27. A needle bar 28 is mounted in the needle bar bushing for endwise reciprocation by a conventional needle bar mechanism (not shown). A needle 29 having an eye 30 is connected to the end of the needle bar.

In order to accommodate the first modification of the invention, a pneumatic valve is formed in the lower needle bar bushing by diametrically opposed holes 31 and 32 in the bushing and a transverse hole 33 through the needle bar. A short tube 34 communicates with one of the holes in the needle bar bushing, and a pneumatic on-oif valve 35 is connected to the free end of the tube. A conduit 36 from a source of compressed air (not shown) is in turn connected to the free end of the pneumatic valve.

Communicating with the other hole 32 in the lower needle bar bushing is a horizontal conduit or tube 37 which is about 18 inches long and composed of brass. The free end of the tube is supported in a groove 38 formed in the top of a support block 39. An outlet nozzle 4% for thread is connected to the tube near the needle bar. The nozzle may be composed of hardened metal, or have a ceramic insert, to alleviate abrasion of thread.

Depending from the free end of the tube is a container 41 for slack thread 42. The container includes a pair of closely spaced parallel walls 43 and 44 or plates. The walls are on the order of two or three thread-diameters apart. The walls are connected at the top to form a roof 45, the peak of which has an opening 46 communicating with the interior of the tube 37. The bottom 47 and sides 4-8 and 49 between the walls are open to provide an outlet or exhaust for compressed air. An inlet 50 for thread is formed in the top of the container. The inlet for thread is in effect located upstream from the outlet for compressed air.

Connected to the sewing table is a conventional thread stand 51. The thread stand has two platforms 52 and 53 and two spool holders S4 and 55, respectively, at an intermediate height, and a crossbar 56 at the top having thread eyelets 57. A block 58 formed with a hole 59 is impaled on one of the spool holders, and a conventional thread tension device 6% is connected to the block. A supply cone 61 of thread 62 is mounted on the other spool holder. The thread tension device serves as a pre-tension device for thread from the supply cone to prevent too much thread from entering the tube.

Mounted inside the work-supporting bed is a conventional loop-taker, indicated generally at 63, which coopcrates with the needle to form lockstitches. The loop taker includes a cup-shaped rotary member 64 which is connected to the end of a bed shaft 65 by setscrews 66 of which only one is shown. A hook beak 67 is formed on the rotary member. Formed in the end of the rotary member is an annular raceway 69 for a bearing rib 7% which is formed around a stationary bobbin case holder 71. The bobbin case holder is held stationary by a lug 72 which is connected to the work-supporting bed and extends into a recess 73 in the bobbin case holder. A semicylindrical gib 74 having a loop-controlling tail 75 is connected to the outer circumferential surface of the rotary member by screws 76 to close the end of the raceway. Also connected to the outer circumferential suriace of the rotary member by screws '77 is a semicylindrical thread guide 78 which serves as a thread pull-oi.

border to facilitate thread pull-off, the loop-controlling tail 75 of the loop-taker is shorter than usual as disclosed in a United States patent of R. E. Johnson, No. 2,657,658, granted November 3, 1953. In addition, a second thread guide 79 is mounted on top of the semicylindric-al thread guide 78 by screws 80 to prevent the hook beak from picking up a double loop.

In operation, in the modification of FIGS. 1 to 3, compressed air with, say, pounds per square inch pressure is continuously introduced into the short tube 34 through the conduit 36 when the pneumatic valve 35 is turned on. The hole 33 in the needle bar is positioned so that it will be in alignment with the holes 31 and 32 in the lower needle bar bushing during the upstroke of the needle when a loop of needle thread seized by the hook beak of the loop-taker is in the cast-off position. With the holes 31, 32 and 33 in alignment, air rushes down the tube 37 to set stitches by imposing tension on the thread 62 and taking up slack thread by aerodynamic friction. The approximately three and one half inches of slack thread 42 which are formed as the needle withdraws from work material (not shown) on the work-supporting bed is collected in the slack thread container 41 which confines the thread to substantially two dimensional movement. If the slack thread container were omitted, the thread would twist and turn in the turbulent air exhaust of the tube and cause thread breakage at sewing speeds comparable to those of modern high speed sewing machines.

The aerodynamic friction between the thread 62'and the compressed air is further aided by an aerodynamic drag force caused by the fiow of air across the loop of thread 42 in the slack thread container 41 and by friction between the tread 62 and the interiors of thread guides such as the tube 37 and the outlet nozzle 40 for thread on the tube. Air which escapes, through the outlet nozzle for thread produces a cooling effect on the thread, the needle, and the work material. In addition, the force of air against the top surface of the work material alleviates puckering of the work material.

The tube 37 is threaded by inserting a length of thread (not shown) into the outlet nozzle 40 for thread and causing air to fiow down the tube. When the end of the thread reaches the outlet for air in the slackthread container 41, the end of the thread is "manually pushed up through the inlet 50 for thread in the top of the slack thread container and tied to the end of the thread from the supply cone 61.

A second modification of the invention is illustrated in FIGS. 4 and 5. FIGS. 6 to 8 illustrate three variations, respectively, of the modification of FIGS. 4 and 5 which may be substituted for the modification of FIGS. 4 and 5. The second modification and the three variations thereof are suitable for use with sewing machines having lower sewing speeds than the sewing speeds contemplated for the modification of FIGS. 1 to 3.

As in the first modification, the second modification of the invention is also illustrated as embodied in a sewing machine having a frame including a work-supporting bed 82, a standard (not shown) rising from one end of the work-supporting bed, a bracket arm 84 at the top of the standard overhanging the work-supporting bed,

and a sewing head 35 at the free end of the bracket arm.

A conduit or tube 86 having an inlet'end 87 for thread 88 is connected to the outside of the sewing head and the bracket arm of the sewing machine. The tube has a bend 89 and an outlet 90 for thread near to and to the outside of the curve of the bend between the bend and the thread inlet end of the tube. The outlet for thread is aimed downstream relative to the movement of thread toward the needle. The tube has a secondary bend 1 to conform to the contours of the sewing head and the bracket arm, and an air hose 92 from a source of compressed air (not shown) is connected to the end of the tube opposite from the inlet end for thread.

In operation, compressed air with, say, 85 pounds per square inch pressure is continuously introduced into the tube 86 through the air hose 92 to set stitches by imposing tension on the thread 88 and taking up slack thread by aerodynamic friction. The aerodynamic friction between the thread 88 and the compressed air is aided by friction between the thread 88 and the tube as the compressed air rounds the bend 89 and forces the thread against the inner circumferential surface of the tube. As in the first modification of the invention and in all subsequent modifications and modified versions, the air produces a cooling effect on the thread, the needle, and the work material, and alleviates puckering of work material. In addition, back-twist, or the build-up of an extra twist in the thread caused by air turbillence, is virtually eliminated.

In the variation of FIG. 6 which may be substituted. for the modification of FIGS. 4 and 5, an outlet tube 93 for thread extends laterally from an intermediate portion of a substantially straight tube 94. The straight tube has an inlet end 95 for thread, and a fitting 96 at the other end for connection to the air hose 92. Both tubes are composed of brass.

In the variation of FIG. 7, a straight tube 97 is formed with diametrically opposed thread-confining slots 98 in an inlet end 99 for thread. An outlet 1&0 for thread is formed in an intermediate portion of the tube and aimed downstream relative to prospective movement of thread toward a needle of a sewing machine. The air hose 92 is connected to the other end 101 of the tube.

In the variation of FIG. 8, a straight tube 102 is formed with a left-hand twist 103 corresponding to the usual left-hand twist of thread. Formed in an inlet end 104 for thread are diametrically opposed thread-confinin g slots 105. The portion 106 of the tube containing the inlet end for thread has a reduced cross sectional area. A venturi pump 107 having a transverse tube 108 at an intermediate portion is connected to the end of the tube 102 opposite from the thread inlet end. The air hose 92 is connected to the free end 169 of the venturi pump, and the transverse tube 108 serves as the outlet for thread.

The operations of the variations of FIGS. 6 to 8 are similar to the operation of the modification of FIGS. 4 and 5.

A third modification of the invention is illustrated in FIG. 9, and a variation thereof is illustrated in FIG. 10. The modification of FIG. 9 is illustrated as embodied in a two-thread chain stitch sewing machine having a frame including a work-supporting bed 110, a standard 111 rising from one end of the work-supporting bed, a bracket arm 112 at the top of the standard overhanging the work-supporting bed, and a sewing head 113 at the free end of the bracket arm. A four-motion looper 114 having an eye 115 is mounted in the work-supporting bed and driven by a looper mechanism of which only a portion, indicated generally at 116, is shown.

The modification of FIG. 9 is similar to the modification of FIGS. 4 and 5 in that a conduit or tube 117 having an inlet end 118 for thread is formed with a bend 119 and has an outlet nozzle 12!) for thread near to and to the outside of the curve of the bend between the bend and the thread inlet end of the tube. In addition, the outlet nozzle for thread is aimed downstream relative to prospective movement of thread. The tube is mounted on, or in, the work-supporting bed between a supply of thread 121 and the looper, and an air hose 122 from a source of compressed air (not shown) is connected to the end of the tube opposite from the inlet end for thread. A thread tension device represented by a snubbing post 123 may be used to act as a pre-tension device to maintain better control over the thread.

The operation of the modification of FIG. 9 is similar to the operation of the modification of FIGS. 4 and 5 except that the compressed air is under very low pressure. Slack thread is taken up during the loop-shedding motion of the looper at which time sufiicient tension is imposed on the thread to set the stitch.

The variation of FIG. is illustrated as embodied in an overedge sewing machine having a frame in the form of a hollow casing 124. An overedge looper 125 and an under looper 126 having eyes 127 and 128, respectively, are mounted in the lower portion of the hollow casing and driven by looper mechanisms of which only portions, indicated generally at 129 and 130, respectively, are shown.

In the variation of FIG. 10, two conduits or tubes 131 and 132 having inlet ends 133 and 134, respectively, for thread from supplies of thread 135 and 136, respectively, are connected to a cylindrical chamber 137. Outlet nozzles 138 and 139 for thread are connected to the chamber diametrically opposite from, and in line with, the tubes 131 and 132, respectively. The chamber has a single inlet tube 140 for air, and an air hose 141 is connected to the air inlet tube from a source of compressed air (not shown). The tubes 131 and 132 are connected to the front of the hollow casing between the supplies of thread and the loopers. As in the modification of FIG. 9 thread tension devices 142 and 143, or snubbing posts (not shown), may be used to act as pretension devices to maintain better control over the thread.

The operation of the variation of FIG. 10 is similar to the operation of the modification of FIG. 9.

Although the invention has been described in its preferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred form has been made by way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and the scope of the invention.

Having thus set forth the nature of the invention, what is claimed herein is:

1. In a sewing machine including a frame, a needle mounted on the frame for endwise reciprocation, a supply of thread for the needle, and a thread handling system for the thread; the improvement wherein the thread handling system comprises a conduit including an inlet through which thread from the thread supply moves toward the needle as required by the needle to form stitches, a container for slack thread defined by two closely spaced parallel walls, said container communicating with the thread inlet of the conduit, and means for causing air to flow cyclically through the conduit counter to said movement of the thread to set stitches by imposing tension on the thread and taking up slack thread by aerodynamic friction.

2. The sewing machine of claim 1 which includes means for imposing tension on the thread before entering the conduit.

3. In a sewing machine including a frame, a bushing in the frame, a needle bar mounted in the bushing for endwise reciprocation, a needle connected to the needle bar, a supply of thread for the needle, and a thread handling system for the thread; the improvement wherein the thread handling system comprises a pneumatic valve formed by a hole formed in the bushing and by a hole formed in the needle bar in a position thereon tor periodic alignment with said hole in the bushing during reciprocation of said needle bar, a conduit through which thread from the thread supply moves toward the needle as required by the needle to form stitches communicating with the hole in the bushing, said conduit having a thread inlet end and an outlet for thread at an intermediate portion, and means for causing air to flow into the hole in the needle bar so that when the holes in the needle bar and the bushing are in alignment air flows through the conduit counter to said movement of the thread to set stitches by imposing tension on the thread and taking up slack thread by aerodynamic friction.

4. The sewing machine of claim 3 which includes a container for slack thread formed by two closely spaced parallel Walls, said container communicating with the thread inlet end of the conduit.

5. The sewing machine of claim 4 in which said con tainer for slack thread has an outlet for air and in which there is an inlet for thread spaced from both said outlet for air and from the thread inlet end of the conduit.

References Cited UNITED STATES PATENTS 1,046,822 12/1912 Madden 242-147 2,599,226 6/1952 Briem. 2,866,424 12/ 1958 Masland 11279 FOREIGN PATENTS 1,070,264 2/1954 France.

JORDAN FRANKLIN, Primary Examiner. G. H. KRIZMANICH, Assistant Examiner. 

